In the southern Central Andes of northwestern Argentina and northern Chile, Ordovician sedimentary rocks occur in the Argentinian Cordillera Oriental mainly in shelf facies, in the westwardly adjacent Puna highlands predominantly in deep marine turbidite facies. Measuring of detailled sedimentological sections and their sequence stratigraphic interpretation together with finds of graptolites in many new localities led to a more detailled subdivision of the c. 7000 m thick basin fill and an analysis of the Ordovician Puna basin and its geodynamic evolution.